Electromagnetic signals are used in many areas for communicating many types of information. In the light spectrum, electromagnetic signals are generally conveyed over optical fibers. In the radio wave spectrum, electromagnetic signals are conveyed via coaxial cables or radiated and picked up by antennas. When the signals are transmitted via a hardware medium, such as a cable or optical fiber, multiple media can be used to increase the volume of transmissible signals. In a single medium, space or even an optical fiber, many issues arise, interference problems, problems with available frequency bands, or with operating the spectrum.
Whenever a frequency band is available, it must not be wasted. Fragmentation of frequency sub-bands within an available frequency band requires greater bandwidth for the same amount of signals to be transmitted.
Seeking optimal frequency band operation while avoiding fragmentation is a constant concern.
The international patent application WO2008/067584 discloses a method wherein baseband digital signals are modulated in adjoining frequency sub-bands. However, this document is limited to teaching how to produce non-fragmented frequency bands when controlling the original, e.g. baseband, signal modulation method.
A problem arises when the signals to be transmitted are not received in baseband, but already modulated in frequency sub-bands using complex coding and protocols.
A recurrent problem then arises when the frequency sub-bands in which the signals are located are distributed in a fragmented manner over one or even several frequency bands. This is the case namely in mobile or cellular telecommunications for which different often separate frequency bands are assigned to each constantly evolving standard, 2G, 3G, 4G.
Then again, the same frequency band can be split among several operators. For the same operator, frequency sub-bands can be distributed in a different way, with intentional or unintentional gaps between uplinks and downlinks or from cell to cell.